Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R). Select your answer from the following options.
Assertion (A): Air transport is a very useful means of transport in mountainous and hilly regions for all.
Reason (B): It is very costly and difficult to construct roads and railways in mountainous regions.
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is not the correct explanation of (A).
3. (A) is true but (R) is false.
4. (A) is false but (R) is true.